Development of Metallic Uranium Recovery Technology from Uranium Oxide by Li Reduction and Electrorefining

Abstract

The purpose of the study is to develop technology for pre-treatment of oxide fuel reprocessing through pyroprocess. In the pre-treatment process, it is necessary to reduce actinide oxide to metallic form. This paper outlines some experimental results of uranium oxide reduction and recovery of refined metallic uranium in electrorefming. Both uranium oxide granules and pellets were used for the experiments. Uranium oxide granules was completely reduced by lithium in several hours at 650°C. Reduced uranium pellets by about 70% provided a simulation of partial reduction for the process flow design. Almost all adherent residues of Li and Li 2 0 were successfully washed out with fresh Liel salt. During electrorefming, metallic uranium deposited on the iron cathode as expected. The recovery efficiencies of metallic uranium from reduced uranium oxide granules and from pellets were about 90% and 50%, respectively. The mass balance data provided the technical bases of Li reduction and refming process flow for design.

Performance of FCCI barrier foils for U–Zr–X metallic fuel

“…Keiser and Cole reported that interdiffusion zone width for the U alloy/Zr diffusion couple is larger than for the U alloy/V when annealed at 700°C for 75 h [15]. Tokiwai et al reported that V foil showed good barrier performance in diffusion couple tests at both 750°C for 2250 h and 750°C 200 h plus 800°C 1 h [13]. The inert interdiffusion behavior of V with U alloys, shown in this study, agreed well with the previous results.…”

“…Another significant result is the relatively poor diffusion barrier performance of Zr, although Zr has been considered to be a strong candidate for FCCI barrier material [12]. Use of Zr foils charged with nitrogen might increase the diffusion barrier performance of Zr because Tokiwai et al showed that Zr foils charged with nitrogen blocked interdifusion of U and Fe due to formation of a very thin ZrN layer, although most Zr foils were dissolved into U-Zr fuel [13].…”

“…Ferritic martensitic steels (FMS) such as HT9 and T91 are considered as candidate cladding materials for a SFR fuel due to their excellent irradiation performance [11]. Recently, a thin coating on the inside wall of cladding has been proposed to retard any interaction between the metallic fuel and its cladding [12,13]. Effectiveness of a Zr liner in mitigating pellet cladding interaction (PCI) for boiling water reactor (BWR) fuel is well established [14].…”

FCCI barrier performance of electroplated Cr for metallic fuel

“…Crawford et al fabricated Zr-sheathed U-Zr metallic fuel and irradiated the fuel in an EBR-II reactor up to 2 at.% of burn-up [4]. Tokiwai et al formed the ZrN layer on HT9 and used a V foil to reduce chemical inter-diffusion [5]. Previous studies on the FCCI barrier have focused mainly on V and Zr of the liner-type.…”

“…They conducted the annealing tests with barrier materials to observe their performance [3][4][5][6]. Keiser and Cole used the V and Zr disks and observed their barrier performance [3].…”